Los Angeles became the largest city in the nation Tuesday to require pet owners to spay or neuter cats and dogs that are 4 months old or older in an effort to reduce the number of unwanted animals in the city.

The City Council's 14-1 vote came with no significant debate, in a sharp contrast to the emotional arguments over the past several months as the measure - based on a stalled state legislative proposal - has made its way through the city bureaucracy.

"This is a huge step forward in making Los Angeles a humane, no-kill city," said Councilman Richard Alarcón, who led the effort to enact the regulation.

"This ordinance will reduce the number of people maimed or killed by animals and decrease by the tens of thousands the number of animals euthanized in our animal shelters....